This invention relates to an exhaust gas oxygen sensor and electrical connector arrangement for electrically connecting the oxygen sensor to an electronic device capable of utilizing an electrical signal produced by the oxygen sensor. The exhaust gas sensor is particularly suited for use in the measurement of the partial pressure of oxygen in the exhaust gases from an internal combustion engine and may be of the type having a ceramic, metal-oxide, oxygen-sensing element. Two metal oxide exhaust gas oxygen sensors are generally known, that is, titania oxygen sensors and zirconia oxygen sensors. Both of these exhaust gas oxygen sensor types are utilized in conjunction with electronic devices that, in response to an oxygen-sensor signal, provide electrical signals used in an engine control system to vary the air/fuel ratio of the mixture supplied to the engine for combustion.
The oxygen sensor and electrical connector arrangement of the invention was particularly designed for use with exhaust gas sensors of the titania type, but is equally adaptable to known oxygen sensors of the zirconia type. These sensors have a cylindrically-shaped member to which one or more electrical terminals are affixed for connection to an electronic circuit.
The oxygen sensors are designed for installation in the exhaust conduit of an internal combustion engine and are provided with threads designed to engage corresponding threads formed in an aperture in the exhaust conduit. Oxygen sensors of prior design have had a pigtail for electrical connection of the sensor to an electronic device. Cooperating male and female connectors have been required to interconnect the end of the pigtail with one or more electrical lead wires from the electronic device. At the connection of the pigtail to the oxygen sensor, a rubber boot has been provided to effect a leak-proof seal.
The exhaust gas sensor is located in an environment that is both very cold under certain environmental conditions and also very hot during normal sensor use. The exhaust gas sensor may reach temperatures up to about 850.degree.C. or higher at the point at which it projects into the exhaust conduit. Moreover, the electrical connection at the oxygen sensor is subject to adverse road conditions that may include salt spray, humidity, water, oil, grease and the exhaust gases themselves. In the use of exhaust gas sensors in feedback fuel control systems, electrical connections between the sensor and the electronic device utilizing its signal are of great importance because failure of any of these connections or changes in their contact resistances can produce signal loss and failure of the closed-loop fuel control system for the engine.